An ink cartridge stores ink to be supplied to an inkjet recording device (inkjet printer). The ink cartridge is provided with an ink storage chamber that stores ink and an ink supply port that supplies ink from the ink storage chamber to the inkjet printer. The ink supply port may also function as an insertion port for an ink extraction tube. When the ink cartridge is not mounted to the inkjet printer, the ink supply port is closed by a valve so that ink will not leak from the ink cartridge.
Mounting the ink cartridge to the inkjet printer is performed by pressing the ink cartridge toward the inkjet printer. In the inkjet printer, a hollow ink extraction tube is protrudingly arranged. When the ink cartridge is mounted to the inkjet printer, the ink extraction tube engages the valve that closes the ink supply port of the ink cartridge, and the ink supply port is opened. By opening the ink supply port, the ink storage chamber and the ink extraction tube are permitted to communicate with each other, and ink is supplied to the inkjet printer via the ink extraction tube.
JP-A-2005-22198 discloses an ink cartridge including an ink supply port having a valve that is urged into a closed position by a coil spring. The ink supply port is opened when the ink cartridge is mounted to an inkjet printer and an ink extraction tube opens the valve by acting against an urging force of the coil spring. When the valve is opened by the ink extraction needle, the ink supply port can supply ink through the ink extraction needle to the inkjet printer.
JP-A-2005-103866 discloses an ink cartridge including a valve element that does not employ a coil spring. The valve element is constructed so as to be slightly deformed by insertion of an ink extraction tube. The slight deformation opens an ink supply port and permits the supply of ink.
As mentioned above, in the ink cartridge disclosed in JP-A-2005-22198, a metal coil spring is used. Accordingly, if a spent ink cartridge is to be properly disposed of, the cartridge must be taken apart so that combustible and incombustible members can be disposed of separately. This requirement increases the complexity of disposal. It would be possible to simply replace the disclosed metal coil spring with an urging member formed of, e.g., a combustible rubber. However, rubber tends to expand in a width direction when compressed, depending on the shape of the rubber object. Accordingly, simply replacing a metal coil spring with rubber urging member presents the problem that as the compressed rubber urging member expands in the width direction and contacts an inner surface of an ink supply port, the force required to insert an ink extraction tube increases, and a valve member cannot be smoothly opened.
The ink cartridge disclosed in JP-A-2005-103866 does not include metal parts, so a complex disposal procedure is not necessary. However, as mentioned above, the valve member of the disclosed cartridge is opened by only slight deformation of the valve member. Thus, if there are any irregularities in the molded valve member, the ink cartridge may leak when it is not installed in an inkjet printer and/or the valve member may not open when the ink cartridge is mounted to the inkjet printer, preventing ink from being supplied to the inkjet printer.